diff -r cf415777a22c -r c8b9943c07eb mercurial/commandserver.py
--- a/mercurial/commandserver.py	Mon May 08 15:31:34 2017 -0700
+++ b/mercurial/commandserver.py	Sun Apr 30 11:08:27 2017 -0700
@@ -409,6 +409,7 @@
 
     def bindsocket(self, sock, address):
         util.bindunixsocket(sock, address)
+        sock.listen(socket.SOMAXCONN)
 
     def unlinksocket(self, address):
         os.unlink(address)
@@ -452,7 +453,6 @@
     def init(self):
         self._sock = socket.socket(socket.AF_UNIX)
         self._servicehandler.bindsocket(self._sock, self.address)
-        self._sock.listen(socket.SOMAXCONN)
         o = signal.signal(signal.SIGCHLD, self._sigchldhandler)
         self._oldsigchldhandler = o
         self._servicehandler.printbanner(self.address)